The present invention relates to photochromatic compounds.
More specifically, the present invention relates to photochromatic compounds belonging to the group of spiro-isoindolino-oxazines, a process for their preparation and their use in polymeric materials.
A further object of the present invention relates to polymeric compositions containing said photochromatic compounds and the photochromatic articles obtained from their processing.
Photochromatic compounds are substances which have the characteristic of reversibly changing colour and/or degree of light transmission when exposed to solar or artificial light in the band ranging from UV to visible, or to some types of electromagnetic radiation, returning to their original state of colour and transmission when the initial light source is removed.
There are numerous substances with photochromatic characteristics, which belong to various groups of both organic and inorganic compounds such as, for example, those described in the texts xe2x80x9cPhotochromismxe2x80x9d, by G. H. Brown (Ed.), Vol. III of the Weissberger series xe2x80x9cTechniques of Organic Chemistryxe2x80x9d, Wiley Interscience, New York (1971) and in xe2x80x9cPhotochromsim: Molecules and Systemsxe2x80x9d, by H. Duerr and H. Bouas-Laurent (Ed.), Vol. 40 of the series xe2x80x9cStudies in Organic Chemistryxe2x80x9d Elsevier (1990).
Among organic photochromatic compounds, those belonging to the groups of spiro-indolino-oxazines, spiro-pyranes and chromenes, are particularly known and used.
The above compounds are capable of giving photochromatic characteristics to polymerized organic materials used, for example, in the production of photochromatic lenses for eye-glasses, special inks, toys, and in many other applications.
As an example, the following patents can be mentioned: U.S. Pat. Nos. 3,562,172, 3,578,602, 4,215.010, 4,342,668, 5,055,576, 5,110,922, 5,186,867, EP 146.135, EP 134.633, EP 141.407, EP 245.020, IT 1.223.348 and IT 1.238.694.
Compounds belonging to the group of spiro-indolino-oxazines have, with respect to other known compounds such as, for example, compounds belonging to the group of spiro-pyranes, the advantage of having a much higher stress resistance when subjected to light and darkness cycles and also have good dyability characteristics.
The Applicant has now found photochromatic compounds belonging to the group of spiro-isoindolino-oxazines which have excellent photochromatic characteristics, excellent stress resistance and high dyability characteristics.
The present invention therefore relates to photochromatic compounds belonging to the group of spiro-isoindolino-oxazines having general formula (I): 
wherein:
a) R represents a linear or branched C1-C10 alkyl group, said alkyl group optionally substituted with 1-10 halogen atoms selected from fluorine, chlorine and bromine, or with hydroxyl groups, linear or branched C1-C6 alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6-tetramethylpiperidine group; a linear or branched C2-C6 alkenyl group; an aryl group selected from phenyl, biphenyl and naphthyl, said aryl group optionally substituted with linear or branched (C1-C6) alkoxyl groups, carboxyl groups, amine groups, N,N-dialkyl (C1-C6) amine groups; a benzyl group;
b) R1 and R2, the same or different, represent a linear or branched C1-C10 alkyl group, said alkyl group optionally substituted with 1-10 halogen atoms selected from fluorine, chlorine and bromine, or with hydroxyl groups, linear or branched C1-C6 alkoxyl groups, carboxyl groups, cyano groups; a linear or branched C2-C10 alkenyl group; a benzyl group; a linear or branched C1-C6 alkoxyl group; an N-alkyl (C1-C6) amine group; an N,N-dialkyl (C1-C6) amine group; or R1 and R2, considered jointly with the carbon atom to which they are bound, represent a C4-C10 cycloalkyl group, said cycloalkyl group optionally substituted with halogen atoms selected from fluorine, chlorine and bromine, or with hydroxyl groups, linear or branched C1-C6 alkoxyl groups, carboxyl groups, cyano groups, amine groups, N-alkyl (C1-C6) amine groups, N,N-dialkyl (C1-C6) amine groups; an N,N-dialkyl (C1-C6) amide group; a cyano group; an aryl group selected from phenyl and biphenyl;
c) R3, R4, R5 and R6 the same or different, represent a hydrogen atom; a halogen atom selected from fluorine, chlorine, bromine and iodine; a linear or branched C1-C6 alkyl group, said alkyl group optionally substituted with 1-6 halogen atoms selected from fluorine, chlorine and bromine, or with hydroxyl groups, linear or branched C1-C6 alkoxyl groups, cyano groups; a benzyl group; a hydroxyl group; a linear or branched C1-C6 alkoxyl group; an amine group; an N-alkyl (C1-C6) amine group; an N,N-dialkyl (C1-C6) amine group; a piperidine, piperazine or morpholine group; a C1-C6 carboxyalkyl group; a C2-C6 carboxyalkenyl group; a carboxyamide group; an N-alkyl (C1-C6) carboxyamide group; an N,N-dialkyl (C1-C6) carboxyamide group; a cyano group; a nitro group; a sulfonic group; an aryl group selected from phenyl, biphenyl and naphthyl, said aryl group optionally substituted with N,N-dialkyl (C1-C6) amine groups, linear or branched C1-C6 alkoxyl groups, hydroxyl groups, linear or branched C1-C6 alkyl groups; an acyl group of the alkyl ketone, aryl ketone or benzyl ketone type; a linear or branched C2-C6 alkenyl group, said alkenyl group optionally subsituted with one or two N,N-dialkyl (C1-C6) 4-aniline groups; an N-2,3-dihydroindoline group; a linear or branched C1-C6 thioether group;
d) two consecutive substituents between R3 and R6, can represent condensation points with other aromatic, heterocyclic or quinonic rings;
e) R7 represents a hydrogen atom; a halogen atom selected from fluorine, chlorine and bromine; a linear or branched C1-C6 alkyl group; a linear or branched C1-C6 alkoxyl group; a phenyl group; a phenoxyl group;
f) P represents a monocyclic or polycyclic aromatic nucleus, belonging to one of the following types: benzenic represented by general formula (II); naphthalenic represented by general formula (III); quinolinic represented by general formula (IV); isoquinolinic represented by general formula (V); cumarinic represented by general formula (VI); quinazolinic represented by general formula (VII); phenanthrenic represented by general formula (VIII); anthracenic represented by general formula (IX): 
xe2x80x83wherein:
at least two adjacent substituents between R8 and R13, R14 and R21, R22 and R28, R30 and R35, R36 and R41, R44 and R47, R48 and R57, R58 and R67, represent the condensation points with the oxazine ring, the other substituents having the same meaning described under point c).
Preferred compounds having general formula (I) for the purposes of the present invention are those in which:
R represents one of the following groups: methyl, ethyl, isopropyl, 2-allyl, 2-hydroxyethyl, 2-carboxymethyl, phenyl, 4-N,N-dimethylaminoaniline, 4-methoxybenzene, 4-cyanobenzene;
R1 and R2, the same or different, represent a methyl or phenyl group; or considered jointly with the carbon atom to which they are bound, represent a cyclohexyl group;
R3, R4, R5 and R6, the same or different, represent a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, or one of the following groups: methyl, isopropyl, hydroxyl, methoxyl, N,N-dimethylamine, piperidine, morpholine, carboxyl, carboxymethyl, N,N-dimethylcarboxyamide, cyano, nitro, methylketone, phenylketone, phenyl;
R7 represents a hydrogen atom, a chlorine atom, a bromine atom, a methyl group or a phenyl group;
P represents one of the groups having general formula (II) to (IX), wherein:
i) two adjacent substituents between R8 and R13, R14 and R21, R22 and R28, R30 and R35, R36 and R41, R44 and R47, R48 and R57, R58 and R67, independently represent the condensation point with the oxazine ring and the other substituents each independently represent a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, or one of the following groups: methyl, isopropyl, hydroxyl, methoxyl, 2-hydroxyethyl, 2-allyl, piperidine, morpholine, N,N-dimethylamine, carboxyl, carboxymethyl, N,N-dimethylcarboxyamide, cyano, nitro, methylketone, ethylketone, phenylketone, methylthiol;
ii) two adjacent substituents between R8 and R13, R14 and R21, R22 and R28, R30 and R35, R36 and R41, R44 and R47, R48 and R57, R58 and R67, different from those specified under point i), represent the condensation point with a benzene or quinone ring.
Specific examples of preferred compounds of the present invention are:
Compound having formula (Ia): 
Compound having formula (Ib): 
Compound having formula (Ic): 
Compound having formula (Id): 
Compound having formula (Ie): 
Compound having formula (If): 
A further object of the present invention relates to a process for the preparation of the photochromatic compounds having general formula (I).
The photochromatic compounds having general formula (I) can be prepared by the condensation of isoindoline compounds having general formula (X): 
wherein the substituents from R to R7 have the same meanings described above, with nitrous compounds having general formula (XI): 
or with aromatic 1,2-quinones having general formula (XII): 
wherein P has the same meanings described above.
The condensation reaction between the isoindoline compounds having general formula (X) and the nitrous compounds having general formula (XI), illustrated in
Scheme I 
is carried out in the presence of an inert organic solvent such as, for example, ethyl alcohol, isopropanol, toluene, or a mixture of these solvents, at a temperature ranging from 50xc2x0 C. to 100xc2x0 C., preferably between 60xc2x0 C. and 75xc2x0 C., for a time ranging from 1 hour to 10 hours, preferably between 2 hours and 5 hours. The reaction product thus obtained is, generally, purified by elution on a silica column and subsequent crystallization from a solvent such as, for example, acetone, toluene, heptane.
The condensation reaction between the isoindoline compounds having general formula (X) and the aromatic 1,2-quinones having general formula (XII) , illustrated in Scheme 2: 
is carried out in the presence of an inert organic solvent such as, for example, ethyl alcohol, isopropanol, toluene, or a mixture of these solvents, and in the presence of aqueous ammonia at 30%, at a temperature ranging from 50xc2x0 C. to 100xc2x0 C., preferably between 60xc2x0 C. and 75xc2x0 C., for a time ranging from 1 hour to 10 hours, preferably between 2 hours and 3 hours. The reaction product thus obtained is, generally, purified by elution on a silica column and subsequent crystallization from a solvent such as, for example, acetone, toluene, heptane.
The isoindoline compounds having general formula (X) can be prepared according to procedures known in the art and described, for example, in: xe2x80x9cTetrahedronxe2x80x9d (1966), Vol. 22, page 2481; xe2x80x9cJournal of Organic Chemistryxe2x80x9d (1979), Vol. 44, page 1519; xe2x80x9cAngewandte Chemie International (1968), Vol. 7, page 373.
The isoindoline compounds having general formula (X) are usually kept in the form of salts such as, for example, iodides, bromides, chlorides, as the tree base is easily oxidated by the air.
The nitrous compounds having general formula (XI) can be prepared by the reaction of phenol compounds with nitrous acid or butyl nitrite, as described, for example, in Italian patent 1.176.858.
The aromatic 1,2-quinones having general formula (XII) can be prepared as described, for example, in: xe2x80x9cJournal of American Chemical Societyxe2x80x9d (1952), Vol. 74, page 278; Chemical Abstract 103-104923q; in European patent EP 245.020 and in U.S. Pat. No. 5,446,150.
Specific examples of isoindoline compounds having general formula (X) are the following, represented by formula (Xa) corresponding to 1,1,2,4,7-pentamethyl-3-methylene-isoindoline and formula (Xb) corresponding to 1,1,4,7-tetramethyl-N-phenyl-3-methylene-isoindoline: 
Specific examples of nitrous compounds having general formula (XI) are the following, represented by formula (XIa) corresponding to 1-nitrous-2-naphthol, by formula (XIb) corresponding to 2-nitrous-1-naphthol, by formula (XIc) corresponding to 5-nitrous-6-hydroxy-quinoline, by formula (XId) corresponding to 1-nitrous-2-naphthol-6-propan(1)one and by formula (XIe) corresponding to 10-nitrous-9-phenanthrol: 
Specific examples of aromatic 1,2-quinone compounds having general formula (XII) are the following, represented by formula (XIIa) corresponding to 1,2-naphthoquinone-4-morpholine, formula (XIIb) corresponding to 1,2-naphthoquinone-4-piperidine and by formula (XIIc) corresponding to 1,2-naphthoquinone-4-(dimethylaniline): 
The photochromatic compounds having general formula (I) of the present invention are colourless or slightly yellowish crystalline products.
Their solutions in common organic solvents such as, for example, benzene, toluene, methanol, when not exposed to light sources are colourless or slightly yellow. These solutions, if exposed to a light source, either visible or UV, become blue-coloured, either sky-blue or blue-green. The colouring quickly diminishes when the light source is removed.
The photochromatic compounds having general formula (I) can be applied to the surface or incorporated in mass into the desired articles, using techniques already known in the art and described hereunder.
Some polymeric photochromatic end-articles can be obtained with moulding techniques such as, for example, injection or compression moulding, starting from polymers in which the photochromatic compound having formula (I) is homogeneously dispersed in mass.
Alternatively, the photochromatic compound having general formula (I) can be dissolved in a solvent, together with the polymeric material such as, for example, polymethyl methacrylate, polyvinyl alcohol, polyvinyl butyral, cellulose acetate butyrate or epoxy, polysiloxane, urethane resin. The mixture thus obtained is deposited on a transparent carrier to form, after evaporation of the solvent, a photochromatic coating.
The photochromatic compound having general formula (I) can also be added to a polymerizable monomer such as, for example, a meth(acrylic) or allyl carbonate monomer, so that, after polymerization carried out in the presence of a suitable initiator such as, for example, azo-bis(isobutyronitrile) in the case of the meth(acrylic) monomer or a peroxyketal in the case of the allyl carbonate monomer, they are uniformly incorporated in the resin formed.
Finally, the photochromatic compound having general formula (I) can be applied to a transparent substrate such as, for example, polycarbonate, polymethyl methacrylate or polydiethylene glycol bis(allyl carbonate), by surface impregnation obtained by putting the substrate in contact, at a suitable temperature, with a solution or dispersion containing the photochromatic compound having general formula (I), operating according to the method described, for example, in U.S. Pat. No. 5,130,353.
The photochromatic compounds having general formula (I) of the present invention have the characteristic of being able to be incorporated in mass or using one of the techniques described above, into various organic polymers such as, for example, high density polyethylene, low density polyethylene, ethylene-vinylacetate copolymer, polyether amides, polypropylene, polymethylmethacrylate, polyvinyl alcohol, polyvinyl butyral, cellulose acetate butyrate, epoxy, polysiloxane or urethane resins, polycarbonate, polydiethylene glycol bis(allyl carbonate), polyamides, polyesters, polystyrene, vinyl polychloride, polymethylacrylate, polyethylacrylate, siliconic polymers.
The photochromatic compounds having general formula (I) of the present invention can be optionally used in the presence of the usual additives for organic polymers such as, for example, phenol antioxidants, sterically hindered amines, benzotriazoles, phosphites or phosphonites.
A further object of the present invention therefore relates to polymeric compositions comprising the above polymeric materials and the above photochromatic compounds having general formula (I), optionally in the presence of the above polymeric additives, and the photochromatic articles obtained from their processing.
The photochromatic compounds having general formula (I) of the present invention, have a photochromatic activity also at room temperature and, surprisingly, in some cases, their photochromatic activity is higher than that of products belonging to the group of spiro-indolino-oxazines.
The photochromatic compounds having general formula (I) of the present invention can be used as such, mixed with each other, or combined with other suitable organic photochromatic compounds to obtain, after activation, the formation of different colourings such as, green, brown and grey. Photochromatic compounds belonging to the group of spiro-indolino-oxazines or spiro-pyranes described in the art such as, for example, in U.S. Pat. No. 5,066,818, are particularly useful for the purpose.